Aftermarket Exhaust Size For 3K

[SurfWagon]

Have tried searching all over the web (including on this site) and even asking a number of exhaust shops. I have a KE36 with a 3K with twin 40mm Dellorto's and a set of 4 into 1 headers. I am trying to work out the best exhaust size and construction to suit this set-up. The car currently has a brand new 2" exhaust with a single rear muffler installed by the previous owner. After driving it back from Brisbane to Melbourne over 2 days I discovered that it was both very loud (with a huge drone) and seemed to create a sense of lag maybe due to turbulence caused by the large sized pipe for a small 1.2lt engine.

 

What I would like to know is what diameter pipe would be suitable (just a weekend cruiser) and how should it be constructed (2 mufflers or a muffler and a resonator) to keep both the noise down and give the engine a little response back.

 

My only thoughts would be for a 1.5" pipe diameter, a mid mounted resonator and a rear mounted muffler.

 

Any help with this would be much appreciated. I am very well versed in terms of race car preparations and high horsepower engines and exhausts but this is something a little from left field.

 

Regards,

 

Luke.

[altezzaclub]

My only thoughts would be for a 1.5" pipe diameter, a mid mounted resonator and a rear mounted muffler.

 

Yep-

 

I took the 2" extractors along a 2" pipe to the longest 2" resonator we counld get, fitted under the passenger's floor as usual.

 

From there it is 1.75" back to a "sports" muffler, an 'open center' tri-chamber that absorbs noise well while still flowing cleanly.

 

That sounds good on the road and is fine inside the car, it runs with a cam and twin SU carbs, although it is still drony after a couple of hours at 100kph.

 

That's all on a 4K. build is here with a couple of sound files-

 

http://www.rollaclub.com/board/topic/42407-the-girls-ke70/

[SurfWagon]

Thanks mate, very good info. Much appreciated.

[B.L.Z.BUB]

2" should be fine. Just whack a second muffler or resonator in.

[Jono.C]

Yeah just put another muffler in it

[bruce]

I had a 2" system, with sports muffler and hotdog resonator, which was droney/loud at 100Km. Replaced the resonator under the passenger side with another muffler and it quietened it down a fair bit, so two mufflers in total. Still kind of had a drone sound present while cruising above 4000rpm with 4 speed. So would recommend to get a 5 speed gearbox and maybe a lower ratio diff to get the revs down, would make highway cruising quieter. Maybe lay some sound deadener under the carpet and boot area.